You don't have time for everything. Therefore, you must choose what to do, but also you must choose what not to do. That is the hard part - choosing what to let go. Once you did that, the rest is (comparatively) easy.
Ideally, devote yourself to one subject and immerse yourself in it. Stay focused, refuse to do anything else. You'll have distractions, you'll doubt your choice, but don't start anything else until you finish what you've started.
If you have to do two things at the time, split your day in two. In the morning do one subject, then take a break (have a lunch, go to walk,...) Then, you study the second one. This break is important, don't jump from one subject to the next without it.
In summary, make your choice and stick to it until completion. Ignore everything else.
Yes, and in my recent experience, following the "pomodoro technique", aka "timeboxing", where you work in 25 minute sprints, with a timer set, and focus on ONE, WRITTEN DOWN task for these 25 minutes, whereafter you take a few minutes break, possibly reconsider if you continue with the same task for the next 25 minutes or choose something else, and then continue.
This can help in this paralyzed kind of state, since it is harder to keep distractions away (and keep 100% focused on one task) for 25 minutes, than for a whole day ... and in those few minutes in between, you are allowed to distract yourself for a very short time.
And to help yourself remember to do your pomodoros, you can use a tool like Beeminder[0], which can track and show you your progress towards your goal as well as act as a commitment device[1] to keep you working on goals over time.
Regarding the switching between different subjects or projects, what helped me was to quickly write down TODO notes of actions I should immediately take when picking up the subject again. For example "Finish exercise X", "Watch lecture Y" or "Run unit tests of project Z".
I found my self dive in to the subject much faster when there was no need to think about where to start.
Often at the end of the day I'll do a mental stack dump of where I am in various projects, including the immediate next steps, in an email and send to myself to easily jump right in the next morning.
Plus one for this. Emailing a a couple of bullet points to yourself at the end of the day so you've got a launch point the following morning really helps avoid that dangerous first 10 minutes in the morning where you sit down at the computer with a coffee and get tempted to click on to HN/reddit/whatever while your brain goes over what to do for the day.
With the list you sent yourself the night before you can dive straight in and avoid getting distracted before you've even started!
you can queue up lots of tasks to be done in the future. when you go to start a new task, you can compare it against everything else in the list to ensure its truly the top priority.
Does that make sense? if not, watch this 5 minute youtube video:
Limiting options is a good strategy. I use a couple of others, which I always think are common sense:
1) Don't study alone. Having a group that is moving in the same direction helps create social pressure, and social pressure makes wonders.
2) Create a finish line and a deadline. They may be fictional, but they must be there. For technical subjects, an applied project is excellent. Say, if you are studying networking, try your hand at writing a protocol analyzer, or a SyncThing client. It must require the theoretical knowledge you are hoping to gain. If you can couple this with strategy (1), some amazing stuff comes out (I always remember fondly a Petri Net state machine compiler I built with four friends in three days flat).
Just playing devil's advocate here, your assumption is that Michael's goals are to master a topic and to gain depth. What if his primary goals are to discover new ideas that he never knew before?
You don't have time for everything. Therefore, you must choose what to do, but also you must choose what not to do. That is the hard part - choosing what to let go. Once you did that, the rest is (comparatively) easy.
Ideally, devote yourself to one subject and immerse yourself in it. Stay focused, refuse to do anything else. You'll have distractions, you'll doubt your choice, but don't start anything else until you finish what you've started.
If you have to do two things at the time, split your day in two. In the morning do one subject, then take a break (have a lunch, go to walk,...) Then, you study the second one. This break is important, don't jump from one subject to the next without it.
In summary, make your choice and stick to it until completion. Ignore everything else.